Re: wsconsctl floating point exception

[Jonathan Gray]

On Fri, Apr 29, 2016 at 03:52:37PM +0200, Mark Kettenis wrote:
> > Date: Fri, 29 Apr 2016 23:12:57 +1000
> > From: Jonathan Gray <j...@jsg.id.au>
> > 
> > On Sat, Apr 23, 2016 at 10:20:15PM +0200, Joerg Jung wrote:
> > > On Tue, Apr 19, 2016 at 10:57:38AM +0200, Caspar Schutijser wrote:
> > > > Hi bugs@,
> > > > 
> > > > On my laptop, wsconsctl crashes with a floating point exception when it
> > > > wants to print keyboard.backlight. It divides by 0.
> > > > 
> > > > Below is a patch that fixes the issue, output from gdb and my dmesg.
> > > 
> > > Yes this is a known problem.  There were some suggestion to fix this not
> > > in wsconsctl (but instead in acpithinkpad?).
> > 
> > Given this still isn't fixed here is a diff to do just that and
> > return an error from the ioctl callback when max is 0.
> > 
> > Index: acpithinkpad.c
> > ===================================================================
> > RCS file: /cvs/src/sys/dev/acpi/acpithinkpad.c,v
> > retrieving revision 1.51
> > diff -u -p -r1.51 acpithinkpad.c
> > --- acpithinkpad.c  10 Jan 2016 16:30:43 -0000      1.51
> > +++ acpithinkpad.c  29 Apr 2016 13:05:02 -0000
> > @@ -630,6 +630,9 @@ thinkpad_get_backlight(struct wskbd_back
> >  
> >     kbl->min = 0;
> >     kbl->max = (sc->sc_thinklight >> 8) & 0x0f;
> > +   if (kbl->max == 0)
> > +           return (-1);
> > +
> >     kbl->curval = sc->sc_thinklight & 0x0f;
> >     return 0;
> >  }
> 
> I think you should return ENOTTY, since that is what
> wskbd_displayioctl() would have returned if we had no keyboard
> backlight.

sure

Index: acpithinkpad.c
===================================================================
RCS file: /cvs/src/sys/dev/acpi/acpithinkpad.c,v
retrieving revision 1.51
diff -u -p -r1.51 acpithinkpad.c
--- acpithinkpad.c      10 Jan 2016 16:30:43 -0000      1.51
+++ acpithinkpad.c      29 Apr 2016 13:58:36 -0000
@@ -631,6 +631,10 @@ thinkpad_get_backlight(struct wskbd_back
        kbl->min = 0;
        kbl->max = (sc->sc_thinklight >> 8) & 0x0f;
        kbl->curval = sc->sc_thinklight & 0x0f;
+
+       if (kbl->max == 0)
+               return (ENOTTY);
+
        return 0;
 }
 
@@ -641,6 +645,9 @@ thinkpad_set_backlight(struct wskbd_back
        int maxval = (sc->sc_thinklight >> 8) & 0x0f;
 
        KASSERT(sc != NULL);
+
+       if (maxval == 0)
+               return (ENOTTY);
 
        if (kbl->curval > maxval)
                return EINVAL;